Components of the Cardiovascular System

Components of the Cardiovascular System

• The cardiovascular system is a closed system of blood vessels (arteries, veins, and capillaries) that circulate blood throughout the body.
• The heart is a muscular pump that propels blood through the vessels.
• Blood carries oxygen, nutrients, hormones, and waste products to and from the tissues.

Blood Vessels

• Arteries carry oxygenated blood away from the heart to the tissues. They have thick, elastic walls to withstand high pressure.
• Veins carry deoxygenated blood back to the heart. They have thinner walls and valves to prevent backflow.
• Capillaries are the smallest blood vessels, connecting arteries and veins. Their thin walls allow for the exchange of substances between blood and tissues.

The Heart

• The heart is a four-chambered organ.
• The right side receives deoxygenated blood from the body and pumps it to the lungs.
• The left side receives oxygenated blood from the lungs and pumps it to the body.
• The heart's chambers are separated by valves that ensure one-way blood flow (tricuspid, mitral, pulmonary, aortic).
• The heart muscle is called myocardium. It has specialized conductive tissues (SA node, AV node, bundle of His, Purkinje fibers) to generate and conduct electrical impulses, coordinating the heartbeat.

Blood

• Blood is a connective tissue composed of plasma and formed elements.
• Plasma is the liquid portion and contains water, proteins, electrolytes, nutrients, hormones, and waste products.
• Formed elements include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
• Red blood cells are responsible for oxygen transport.
• White blood cells are part of the immune system, involved in fighting infection.
• Platelets are essential for blood clotting.

Cardiovascular Function

• Cardiac output is the volume of blood pumped by the heart per minute. It is determined by heart rate and stroke volume.
• Heart rate is the number of beats per minute.
• Stroke volume is the volume of blood pumped per beat.
• Blood pressure is the force exerted by blood against the walls of blood vessels. It's measured as systolic (highest pressure during contraction) over diastolic (lowest pressure during relaxation).
• High blood pressure (hypertension) is a significant risk factor for cardiovascular disease.
• Blood flow is regulated by the constriction and dilation of blood vessels, influenced by factors like local metabolic needs.

Cardiovascular Regulation

• The cardiovascular system is regulated by the autonomic nervous system (sympathetic and parasympathetic branches) and hormones (e.g., epinephrine, norepinephrine).
• The sympathetic nervous system increases heart rate and contractility (strength of contraction), generally for "fight-or-flight" responses.
• The parasympathetic nervous system decreases heart rate.
• Hormones like epinephrine can significantly impact heart rate.

Diseases and Disorders

• Hypertension (high blood pressure) is a major risk factor for stroke, heart attack, and kidney disease.
• Arteriosclerosis (hardening of the arteries) is a gradual process involving plaque buildup in artery walls and can increase blood pressure.
• Atherosclerosis is a type of arteriosclerosis characterized by plaque formation in arteries, a key risk factor for coronary artery disease.
• Coronary artery disease results from the narrowing, blockage, or spasm of the arteries that supply blood to the heart muscle, potentially leading to heart attack or angina.
• Heart attack (myocardial infarction) occurs when blood flow to a part of the heart muscle is blocked.
• Stroke happens when blood flow to the brain is interrupted, either through blockage or rupture of a blood vessel.
• Congestive heart failure occurs when the heart cannot pump enough blood to meet the body's needs, causing fluid buildup in the lungs or other tissues.
• Valve disorders can lead to issues with blood flow through the heart chambers.